66 ACTINOMYCETES 



speculation, but no spores are produced; this type of mycelium usually 

 becomes gray with continued incubation. On other media, the aerial myce- 

 lium forms a rather fluffy mat, white in color; it turns slightly pink when 

 sporulation occurs. No spirals have been observed. None of the common 

 media will induce sporulation. It occurs best after 10 to 14 days' incubation 

 on a carbon-free salt agar, to which 0.5 per cent soluble starch has been 

 added. Inositol and mannose will also support sporulation, but they are 

 not as satisfactory carbon sources for this purpose as starch. The only other 

 medium on which spores are found is nitrogen-free synthetic agar to which 

 0.2 per cent glycine or asparagine is added. The spores are coccoid to oval 

 1.1-1.6 by 0.7-1.1 p. 



Synthetic agar: Growth sparse, white; aerial mycelium white; no sporu- 

 lation; no soluble pigment. 



Nutrient agar: Growth moderate, cream-colored; no aerial mycelium; 

 soluble pigment light yellow-brown. 



Potato: Growth luxuriant, spreading, cream-colored; aerial mycelium 

 gray; soluble pigment light brown turning dark brown after 30 days' in- 

 cubation. 



Gelatin: Growth cream-colored to brown. Liquefaction rapid. Soluble 

 pigment dark brown. 



Milk: Growth dark brown to black. No coagulation. Peptonization rapid. 

 Soluble pigment brown. 



Starch: Hydrolysis. 



Nitrate: Reduction negative. 



Glucose-asparagine agar: Growth moderate; aerial mycelium powdery 

 white; no pigmentation, no sporulation. 



Calcium malate: Growth moderate, white; aerial mycelium white; no 

 soluble pigment; no sporulation. 



Oatmeal agar: Growth luxuriant, brown; aerial mycelium abundant, 

 fluffy, white; no sporulation; no soluble pigment. 



Antagonistic properties : Produces hydroxystreptomycin. 



Remarks: Carbon sources rapidly utilized: glucose, dextrin, starch, 

 glycerol, calcium malate, and sodium succinate. Several assimilated slowly: 

 mannose, maltose, inositol, and sodium acetate. Others not utilized: xylose, 

 galactose, sorbose, sucrose, cellobiose, melibiose, lactose, mannitol, sorbitol, 

 sodium citrate, and potassium sodium tartrate. Among the several nitrogen 

 sources investigated, (NH 4 ) 2 HP0 4 , urea, asparagine, glycine, and arginine 

 support moderate to rapid growth; NaN0 3 supports slow growth; tryp- 

 tophane, tyrosine, and methionine are not satisfactory nitrogen sources. 



48. Streptomyces viridoflavus n. sp. Waksman and Taber. 

 Vegetative growth: Abundant lichnoid growth on most media; color of 

 growth yellow-green, turning olive-green to almost brown. Soluble pigment 



